This invention relates to containers or drums used for packaging wire coils, and more specifically, to an improved bottom assembly for such containers or drums.
FIGS. 1 and 2 of the accompanying drawings illustrate a conventional wire-coil packaging drum 10 as disclosed in U.S. Pat. No. 5,105,943 to Lesko et al. (incorporated herein by reference). The drum 10, which is ordinarily made of pasteboard, includes a cylindrical drum body 12 and a bottom assembly 16 designed to anchor a hold-down system (to be described below) for a wire coil 30 received in the drum. The hold-down system serves as a dunnage for the wire coil during transport—specifically by applying a compressive force to the top of the coil to reduce shifting of the coil due to vibration and other movement of the drum.
The drum bottom assembly 16 includes a bottom heading 14 and a fixed-length strap 18 which is bent to form an upwardly (as shown) projecting central loop 20. The opposite end portions 22 of the strap are secured to the upper surface of the bottom heading by stapling, and an annular disk 24 is glued to the upper surface so as to cover the opposite ends of the strap and also to increase the strength of the drum bottom.
The hold-down system includes an elastic cord 34 provided with a hook 36 and a loop 38 at its opposite ends, respectively. An optional tubular, pasteboard core member 28 may be fitted over the looped portion 20 of strap 18 and received in a central opening 24a of the annular disk, where it is secured by gluing. The wire coil 30 is ordinarily formed directly in the drum by feeding the wire from a processing machine into the drum while rotating the drum about its central axis. Once the coil has been formed, the hold-down system is completed by upwardly stretching the elastic cord 34, hooked to the central loop 20, and passing a rigid bar 32 through the loop 38. The bar thus provides continuous compressive engagement with the coil under the tension of the elastic cord. The bar may compress the coil through the intermediary of an upper annular disk 40, which may be constituted by a pair of disk halves 42, as shown. Upon completion of the hold-down system, the drum may be sealed by attachment of a suitable top heading 46.
Although effective for its intended purpose, the above-described arrangement of the Lesko et al. patent is subject to several disadvantages in practice. For example, the fixed-length strap is attached to the upper surface of the bottom heading by staples or the like. This is a costly and labor-intensive operation. Further, this operation is performed before attaching the bottom heading to the drum body, thereby complicating the drum assembly process.
Other disadvantages stem from the fact that the elastic cord is not adjustable. As a result of this, the compressive force applied to the wire coil by the elastic cord cannot be adjusted. Further, the cord is limited to use only with drums within a certain height range. In order to accommodate drums over a wide range of heights, or to be able to adjust the amount of compressive force to be applied to a particular coil, it is necessary to maintain a supply of elastic cords having different lengths. This is inconvenient and leaves open the possibility that an assembly worker will mistakenly select an elastic cord of an incorrect length, so that the wire coil is not properly secured by the hold-down system.
One attempt to simplify the drum assembly process of the above-described arrangement is disclosed in U.S. Pat. No. 5,819,934 to Cooper (also incorporated herein by reference). The Cooper patent describes an arrangement in which a fixed-length strap is attached to the central tubular core rather than to the drum bottom heading. This eliminates the need to secure a strap to the bottom heading before the heading is attached to the drum body. However, the attachment of the strap to the core still constitutes a costly and labor intensive operation. In addition, the Cooper patent does not address the problems stemming from lack of adjustability of the elastic cord.
Accordingly, there remains a need for an improved construction that avoids the aforementioned disadvantages of the structure described in the Lesko et al. patent.